Safety fuel system for engines



1958 J. E. ESHBAUGH 2,857,904

SAFETY FUEL SYSTEM FOR ENGINES Filed Aug. 20, 1956 A amp/#9444 PUMP INVENTOR. 0255a 45 'sfifiaqgi Q 21$ Arromvr United States Patent SAFETY FUEL SYSTEM FORENGINES Jesse E. Eshbaugh, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 20, 1956, Serial No. 605,063 7 Claims. or. 123-193 This invention relates to fuel systems and more particularly to engine fuel systems normally closed to the atmosphere for combating vapor lock.

When diaphragm type pumps are utilized in fuel feed systems and particularly in automotive vehicles, vapor is often generated in the fuel tank and feed line by a condition such as high ambient temperature or high fuel volatility. Vapor which may be present in the feed line passes through the spring biased inlet and outlet valves of the pump but operation of the pump will not develop the fuel pressure above that existent in the tank. This situation may be overcome by employing a closed systemi. e.a system sealed from the atmosphere and in which vapor pressure developed above the liquid level in the fuel tank is employed in filling the feed line with liquid fuel so that the pump may operate and efiiciently develop the proper discharge pressure. A further difliculty has heretofore arisen, however, in that fuel will continue to be discharged because of the vapor pressure and after the engine is stopped and thereby flood the carburetor or will leak out as a fire hazard especially in the event the fuel line breaks due to accident or other cause.

It has now been found that vapor lock may safely be overcome by pressurization of the fuel tank because of a provision for automatically venting the tank of fuel vapor pressure independently ofthe feed line when liquid fuel discharge through the latter is not desired.

An object of the present invention is to provide an improved fuel system using the vapor pressure of the fuel to combat vapor lock and which is effective to supply liquid fuel from a source of supply such as a tank only when the engine being served is operated or when the liquid fuel discharge pressure is above a predetermined minimum. Another object is to provide a vent for excess fuel vapor pressure in a pressurized fuel system and which will, in the interest of safety, interrupt liquid fuel flow induced by vapor pressure and in the event of engine or fuel line failure.

To these ends, a feature of the invention pertains to a fuel vapor pressure vent with means for actuating the vent dependent upon the pressure existent in the liquid fuel discharge line of a normally closed fuel system. Another feature pertains to a normally closed fuel system employing a diaphragm type pump for supplying liquid fuel to the fuel feed line of an engine combined with means sensitive to at least one of the operation conditions of the engine to vent the tank of vapor pressure when liquid fuel flow is not desired. Another feature is an electrical contact arrangement associated with the fuel and ignition systems of an engine whereby a drop in a minimum controlling pressure related to the engine operation renders the ignition circuit ineffective.

The invention will now be more particularly described by referring to the accompanying drawing and by being thereafter pointed out in the claims.

In the drawings:

Fig. 1 is a somewhat diagrammatic view illustrating an "ice engine fuel system as one embodiment of the present invention and omitting the carburetor and intake manifold portions which may be conventional; and

Fig. 2 is a view taken in section along the line 2-2 of Fig. 1 and drawn to a smaller scale.

The diagrammatic representation in Fig. 1 discloses a vehicle fuel tank 10 tightly closed by means of a filler cap 12. One end of a fuel feed line 14 terminates close to the bottom of the interior of tank 10. That line serves a pump 15 of the diagram type and communicates by means of a line 16 with the carburetor of an engine, not disclosed. By way of example only, a pump may be used such as disclosed in the United States Patent 2,308,041 granted January 12, 1943, in the names of A. M, Babitch and G. W. Harry. Another branch 18 of the feed line extends to a container 20 located remotely from the fuel tank 10, This container could be placed. under the hood of an automotive vehicle. The container 20 is perforated as at 22 for communication with the ambient atmosphere.

The top of the tank 10 is fitted with an outlet fixture 24 communicating by means of a vent line 26 to the under portion of the container 22. The fixture 24 bears a threaded portion 28 which extends into the tank 10 and is threaded to receive an annular member 30 having openings 32 and 34. The fixture 24 is flanged as at 25 so as to cooperate with the member 30 and thereby be tightly held to the top wall of the tank 10. The fixture 24 has an elongated chamber 36 with a conical seat 38 at one end. Opposing and spaced from the conical seat 38 is a partition 40 and loosely interposed between the partition 40 and the seat 38 is a ball 42. This ball is of less diameter than the chamber 36.

Inside of the container 20 is fixed a vertical housing 46 with which one end of the vent line 26 communicates. The upper marginal edge of the housing 46 is flanged tightly to receive the periphery of a seal disk or valve seat 48 which is centrally apertured as at 50.

An inverted cup member 52 is located above the housing 46 and is provided with a vertical central stem 54 defining an air vent passage 55. This passage is open at its upper end to the ambient atmosphere. The bottom marginal portion of the cup 52 is crimped as at 58 about the circular margin of a valve disk 60. This disk bears an annular and downwardly extending ridge 62 adapted normally to seat upon the disk.48 around the aperture 50. The valve disk is perforated as at 64 and 66 and is biased downwardly by a coil spring 68, the lower end of which is fastened or attached to a bar 70 welded across but only partially restricting one end of the vent line 26. A partition 72 is fixed in a horizontal plane across the interior of the cup member 52 and this partition is apertured as at 74 and 76. A valve member 78 is arranged to bear upwardly against circular flange portions of the partition 72 which define the openings 74 and 76. A coil spring 80 is arranged to bear against a head 82 on a valve pin 84. The spring 80 serves normally to retain the valve 78 in its closed position.

Mounted upon two adjacent walls of the container 20 are two diaphragm type motors and 92. The axes of these motors are placed in vertical planes which are at right angles to each other.

The motor 90 includes cup members 94 and 95 placed in opposed relation and tightly clamped together at their peripheries with a flexible diaphragm 96 interposed. The central portion or the diaphragm 96 is clamped between two circular plates 98 and 100 held together by means of a head 102 and shoulder portion 104 formed on a stem 106. This stem freely extends through an opening 108 in the cup member 95 and has a hooked end 109 partially surrounding the vertical stem 54. A short arm 110 is fixed to the stem 106 and is provided with an electrical contact 112. This contact is normally out of engagement with a contact 114 which is connected by a line 116 to the ignition circuit represented generally as at, 118. This circuit is shown to include a spark plug 120, a distributor 122, an ignition switch 124, a battery 126 and a ground connection 128. A coil spring 130 surrounds the stem 106 and serves, with the aid of the liquid fuel pressure, to maintain the diaphragm 96 in its proper operating position as will further appear. The contact 112 is connected to a stationary contact 132 which normally is in engagement with a contact 134 and supported on one end of a lever 136 pivotally supported as at 138. The other end 140 of the lever 136 is so arranged as to be in operating position with relation to an arm'142 as is best seen in Fig. 2. The arm 142 is fixed to a stem 144 similar in all respects to the stem 1% in its relation to the vent stem 54 but forming a part of the motor 92. The latter is structurally the same as the motor 90 but instead of being connected to the liquid fuel line 18, it is connected by a line 146 leading to the oil pressure system of the engine. The line 146 is restricted as at 148 for a purpose to be described hereinafter.

In operation of the system it will be seen that, in the event the vehicle employing the system should be upset, the ball 42 would engage the conical seat 38 and prevent the flow of liquid fuel by way of the line 26. At all other times the ball 4-2 would be of no effect as the design is such that venting vapor would have insufficient force to seat the ball.

In normal operation, the ball 42 rests in its position as shown in Fig. l and is ineffective and the vent line 26 is closed from the atmosphere because of the valve disk 60 and valve member 78. Venting through the line 26 will occur when or if excessive vacuum is created within the tank in which event the spring tit will yield and the valve 78 will admit sufficient air from the passage 55 to relieve the condition. The air will enter through the perforations 64 and 66 to pass through the aperture 50 and by way of the vent line 26 into the tank 11). Admission of air to the tank will cease obviously depending upon the predetermined loading of the spring 3%.

Assuming that the diaphragm type pump is drawing fuel from the tank 10, that fuel will flow to the car buretor by way of the branch line 16 and the pressure of the fuel as discharged from the pump Will be exerted against the diaphragm 96. The diaphragm will assume a position dependent upon the predetermined loading of the spring 130. Under normal operating conditions the hooked end 109 will not interfere with the stem 54 and the contacts 112 and 114 will be in the positions as shown in Fig. 1. The engine being served will operate and it lubricating oil pressure will be exerted through the line 146 against the diaphragm in the motor 92 in such a way as not to affect the stem 54 and not to interfere with the contacts 132 and 134 being in contact. In this situation the engine operates and vapor in the feed line 14 due to high ambient temperature is combatted by the vapor pressure generated within the tank 10. This pressure causes liquid fuel to flow into the pump 15 and the possibility of fuel supply failure due to vapor lock is eliminated.

In the event of a rupture in the fuel feed line 14 or the branch line 16 or 18, a fire hazard promptly would arise except for the provisions taken to terminate the fuel flow. With a rupture in the fuel line, the pressure within the motor 90 would be reduced with the result that the stem hook 108 would tip the cup 52 in a clock- ,wise direction as viewed in Fig. 1, thereby to unseat the valve disk 60 and cause the venting of the tank 10 by way of aperture 50. At the same time, the motion of the stem 106 and the arm 110 would cause the contact 112 to engage the contact 114 and the ignition system 118 1y despite a possible momentary and slight continued flow of fuel to the carburetor.

A failure of the lubricating oil pressure on the engine would cause the motor 92 to tip the cup 52 and again vent the gas tank 16 through the line 26 and the opening 50. In this case the contacts 132 and 134 would separate. The purpose in using the latter contacts for grounding the ignition circuit is to permit engine starting. When starting and before an adequate engine oil pressure is developed, the contacts 132 and 134 must be open to prevent grounding of the ignition circuit through the closed contacts 112 and 114.

I claim:

1. A fuel system for an engine including a closed fuel supply tank, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump associated with said feed line, a vent line connected to the top portion of said tank, a valve normally closing said vent line, means responsive to a predetermined condition which has become abnormal and inconsistent with said engine operation such as the oil pressure, and means connecting said responsive means to said valve for opening the latter,

2. A fuel system for an engine including a closed fuel supply tank, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump associated with said feed line, a vent line communicating with the top portion of said tank, a valve controlling said vent line, and means responsive to the lubricating oil pressure in said engine inconsistent with operation of the latter for opening said valve.

3. A fuel system including a closed fuel supply tank, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump associated with said feed line, a vent line connected to the top portion of said tank, a valve normally closing said vent line, and means responsive to abnormal fuel pressure in said feed line for opening said valve.

4. A fuel system for an engine including a closed fuel supply tank, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type 'pump associated with said feed line, a vent line connected to the top portion of said tank, a valve normally closing said vent line, means responsive to abnormal oil pressure of said engine and to abnormal fuel pressure in said feed line for controlling said valve.

5. A fuel system for an engine including a closed fuel supply tank, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump associated with said feed line, a vent line connected to the top portion of said tank, a valve remote from said tank and normally closing said vent line, and means responsive to abnormal predetermined pressures in the lubricating oil system of said engine and in said feed line for opening said valve.

6. A fuel system including a closed fuel supply tank for serving an engine, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump associated with said feed line, a vent line communicating with the top portion of said tank, a check valve arranged normally to permit vapor to enter said vent line from said tank, a second valve normally controlling said vent line, means responsive to a predetermined pressure inconsistent with engine operation such as the fuel pressure for opening said second valve, and an electrical contact arrangement adapted to be operated by said responsive means for rendering the ignition circuit of said engine inoperative when said second valve is opened.

7. A fuel system including a closed fuel supply tank for serving an engine, an engine feed line communicating with a zone in a bottom portion of said tank, a diaphragm type pump arranged in said feed line, a vent line with one end connected to a top portion of said tank to receive vapor therefrom, a check valve located between said tank and vent line and arranged normally to permit vapor to enter said vent line from said tank, a second valve remote from said tank and normally controlling said vent line, means responsive to two predetermined pressures pertaining to the operation of saixl engine such as the oil and fuel pressures and arranged to open said second valve when subnormal conditions exist, and an arrangement associated with the ignition circuit of said engine and connected to said responsive means whereby the said engine is rendered inoperative under said subnormal conditions.

References Cited in the file of this patent UNITED STATES PATENTS 

